US5502508A - Gradation compensating apparatus for a video signal - Google Patents

Gradation compensating apparatus for a video signal Download PDF

Info

Publication number
US5502508A
US5502508A US08/268,302 US26830294A US5502508A US 5502508 A US5502508 A US 5502508A US 26830294 A US26830294 A US 26830294A US 5502508 A US5502508 A US 5502508A
Authority
US
United States
Prior art keywords
signal
compensating
detecting
skin color
controlling
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US08/268,302
Other languages
English (en)
Inventor
Minoru Kawabata
Atsuhisa Kageyama
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Panasonic Holdings Corp
Original Assignee
Matsushita Electric Industrial Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Matsushita Electric Industrial Co Ltd filed Critical Matsushita Electric Industrial Co Ltd
Assigned to MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD. reassignment MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KAGEYAMA, ATSUHISA, KAWABATA, MINORU
Application granted granted Critical
Publication of US5502508A publication Critical patent/US5502508A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
    • H04N5/57—Control of contrast or brightness
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/14—Picture signal circuitry for video frequency region
    • H04N5/20—Circuitry for controlling amplitude response
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/64—Circuits for processing colour signals
    • H04N9/68—Circuits for processing colour signals for controlling the amplitude of colour signals, e.g. automatic chroma control circuits
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/64—Circuits for processing colour signals
    • H04N9/73—Colour balance circuits, e.g. white balance circuits or colour temperature control

Definitions

  • the present invention relates to a gradation compensating apparatus for a video signal for improving a television picture quality.
  • gradation compensating apparatus for video signals have been recognized as being important for realizing high picture quality. Specifically, high picture quality is realized by preventing picture suppression and black level buoying. As a result, by improving the picture gradation, the devices have been found to be useful for large color television receivers and for applications where high picture quality is required.
  • FIG. 1 shows input-output characteristic curves of a black level compensating circuit of a gradation compensating apparatus for a video signal in accordance with the prior art.
  • the abscissa is an input voltage level and the ordinate is an output voltage level.
  • the abscissa marked 1 shows an input voltage level corresponding to the minimum brightness level and the range marked 2 shows an input voltage level corresponding to the brightness of a skin color portion of the input video signal.
  • the curve 3 shows an input-output characteristic without compensation and the output voltage level is proportional to the input voltage level.
  • the curve 4 shows a characteristic with compensation.
  • the minimum brightness level when the minimum brightness level is as marked by 1, the picture appears as if its black level is buoyant.
  • the minimum brightness level is lowered to a level which is lower than that of the input and there is no level drift due to black level compensation.
  • the slant of the characteristic curve 3 without compensation is made steep and the input voltage level of the minimum brightness level is compensated to approach the pedestal level.
  • APL average picture level
  • a gradation compensating apparatus for a video signal of the present invention comprises a skin color detecting circuit, a compensation amount control circuit, an APL detecting circuit, an APL controlling circuit, a contrast controlling circuit, a compensation quitting circuit, and an output circuit.
  • the skin color portion of the video signal is detected from the input color difference signal at the skin color detecting circuit and then the level is adjusted at the compensation amount controlling circuit to employ the skin color detecting signal as a compensating signal.
  • the APL level is detected from the input luminance signal at the APL detecting circuit, and the APL voltage is outputted from the APL detecting circuit.
  • the compensating signal level is adjusted according to the APL voltage at the APL controlling circuit. In this manner, the compensation is increased for a picture which has a high APL level and a skin color which is easy to dull.
  • the compensating signal level is controlled at the contrast controlling circuit by using a contrast adjusting voltage.
  • the compensation is stopped for the letter portion to display on the screen at the compensation quitting circuit. Also, the compensating output voltage is obtained at the output circuit, and the compensation is excuted by using this compensating output voltage.
  • FIG. 1 shows input-output characteristic curves of a black level compensating circuit, which is an example of a gradation compensating apparatus for a video signal in accordance with the prior art.
  • FIG. 2 is a block diagram of a gradation compensating apparatus for a video signal in accordance with a preferred embodiment of the present invention.
  • FIG. 3 shows a characteristic curve of a skin color detecting circuit in a gradation compensating apparatus shown in FIG. 2 in accordance with the preferred embodiment of the present invention.
  • FIG. 4 shows a characteristic curve of an APL control circuit in a gradation compensating apparatus shown in FIG. 2 in accordance with the preferred embodiment of the present invention.
  • FIG. 5 shows a block diagram of a gradation compensating apparatus in accordance with another embodiment of the present invention.
  • FIG. 6 is a block diagram of a gradation compensating apparatus in accordance with still another embodiment of the present invention.
  • FIG. 2 is a block diagram of a gradation compensating apparatus for a video signal in accordance with a preferred embodiment of the present invention.
  • a skin color detecting circuit 1 detects a signal from a skin color portion of an input color difference signal a.
  • a compensation amount controlling circuit 2 adjusts the level of the skin color detecting signal which is detected at the skin color detecting circuit 1 and outputs it as a compensating signal.
  • An APL circuit 3 detects an APL level from the input luminance signal b.
  • An APL controlling circuit 4 adjusts the level of the compensating signal d by using the APL detecting voltage e detected at the APL detecting circuit 3 and outputs APL control compensating signal f.
  • a contrast controlling circuit 5 adjusts the level of the compensating signal d by using the contrast adjusting voltage g (variable dc voltage) and outputs a compensating signal i.
  • a compensating quitting circuit 6 quits compensation action for a letter displaying portion on the screen.
  • An output circuit 7 controls the inputted dc reference voltage 1 based on the compensating current j outputted from the compensation quitting circuit 6 and outputs a compensating output voltage k.
  • a CRT driving circuit 8 increases the skin color brightness on the screen by using the compensating output voltage k outputted from the output circuit 7 as a cutoff reference voltage. Thus, when the cutoff reference voltage is reduced, the picture brightness increases.
  • FIG. 3 shows a characteristic curve of a skin color detecting circuit 1 which detects the skin color portion of the input color difference signal.
  • the skin color detecting circuit 1 detects the minimum value of the positive side of the reverse waveform of the color difference signal (B-Y) and the minimum value of the positive side waveform of the color difference signal (R-Y).
  • the amplitude of the color difference signal (R-Y) is controlled so that the detection characteristic becomes maximum at the skin color hue, namely 123 degrees. Because the skin color detecting signal c is used as a compensating signal as it is, the amplitude of the signal is limited near the saturation point of the skin color to prevent excessive compensation when the highly saturated signal is inputted.
  • the amplitude of the signal which is detected is adjusted to the value which is optimum for compensation at the compensation amount controlling circuit 2.
  • the average picture level (APL) of the picture is detected from the input luminance signal b and the APL voltage e is outputted.
  • the compensating signal d is controlled using the inputted APL detecting signal e so that the compensation does not occur for a dark picture and does occur for a light picture as shown in FIG. 4.
  • the compensating signal is outputted to the CRT driving circuit 8
  • the compensating signal is independent of various kinds of picture controllers. Therefore, because the compensation amount, i.e.
  • the contrast and the compensation amount are linked together at the contrast controlling circuit 5 using a contrast adjusting voltage g.
  • the information letters displayed on the screen by a microcomputer for channel selection are also compensated and brightness nonuniformity occurs in the displayed letters. Therefore, the compensation quitting circuit 6 quits the compensation at the information letter portion, by using a compensation quitting signal h which contains information as to whether there are information letters on the screen, and outputs a compensating current j.
  • the output circuit 7 controls the compensating current j by the reference voltage 1 and outputs a compensating output voltage k.
  • the CRT driving circuit 8 lowers each cutoff voltage of the R, G, and B guns only for the skin color portion by using the compensating output voltage k as a cutoff reference voltage, and increases the brightness of the skin color in the picture. As a result, the dullness of the skin color is improved.
  • a gradation compensating apparatus can improve dullness of the skin color, by controlling the signal detected at the skin color detecting circuit 1, at the compensation amount controlling circuit 2, the APL controlling circuit 4, the contrast controlling circuit 5, and the compensation quitting circuit 6, and by outputting the compensating output voltage k from the output circuit 7 to the CRT driving circuit 8.
  • FIG. 5 is a block diagram of a gradation compensating apparatus for a video signal in accordance with another embodiment of the present invention.
  • the circuits from the skin color detecting circuit 1 to the APL controlling circuit 4 are similar to those in the first preferred embodiment.
  • the output circuit 7 compensates the input luminance signal b by using the APL control compensating signal f outputted from the APL controlling circuit 4.
  • the output circuit 7 executes a compensation process by controlling the input luminance signal q with negative polarity (positive sync) by the APL control compensating signal f outputted from the APL controlling circuit 4 and by outputting a compensating luminance voltage m. Because the output circuit 7 inverts the polarity of the APL control compensating signal f, and controls the input luminance signal q, and outputs the compensating luminance voltage m, when the luminance signal with negative polarity is inputted, the signal level for the skin color portion only is increased by the compensating signal f. Thus, the brightness of the skin color portion in the picture is increased, and the dullness of skin color is improved.
  • a gradation compensating apparatus for a video signal can be presented with increased brightness for the skin color portion and improved dullness of the skin color.
  • FIG. 6 is a block diagram of a gradation compensating apparatus for a video signal in accordance with still another preferred embodiment of the present invention.
  • the circuits from the skin color detecting circuit 1 to the compensation quitting circuit 6 are similar to those in the first preferred embodiment.
  • the output circuit 7 controls the compensating current j outputted from the compensation quitting circuit 6 by a dc voltage n, executes a compensation process and outputs a compensation output signal v.
  • the output circuit 7 controls the compensating current j outputted from the compensation quitting circuit 6 by the dc voltage n and outputs the compensating output voltage o.
  • the compensation output signal o By inputting the compensation output signal o to an adder circuit 9, by outputting the brightness controlling current p, and by controlling the user adjusting value of a brightness controlling circuit 10 by the brightness controlling current p, the brightness of the skin color portion is increased and the dullness of the skin color is improved in the picture.
  • a gradation compensating apparatus by controlling the skin color detecting signal c detected at the skin color detecting circuit 1 through the compensation amount controlling circuit 2, the APL controlling circuit 4, the contrast controlling circuit 5, and the compensation quitting circuit 6, and by varying the brightness through the output circuit 7, the adder circuit 9, and the brightness controlling circuit 10, a gradation compensating apparatus can be presented with improved dullness of the skin color.
  • a carrier chrominance signal can be also used instead of the color difference signal.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Processing Of Color Television Signals (AREA)
US08/268,302 1993-07-28 1994-06-30 Gradation compensating apparatus for a video signal Expired - Lifetime US5502508A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP05186051A JP3136850B2 (ja) 1993-07-28 1993-07-28 映像信号の階調補正装置
JP5-186051 1993-07-28

Publications (1)

Publication Number Publication Date
US5502508A true US5502508A (en) 1996-03-26

Family

ID=16181542

Family Applications (1)

Application Number Title Priority Date Filing Date
US08/268,302 Expired - Lifetime US5502508A (en) 1993-07-28 1994-06-30 Gradation compensating apparatus for a video signal

Country Status (8)

Country Link
US (1) US5502508A (ja)
EP (1) EP0637166B1 (ja)
JP (1) JP3136850B2 (ja)
KR (1) KR970006659B1 (ja)
CN (1) CN1085926C (ja)
AU (1) AU674235B2 (ja)
CA (1) CA2128758C (ja)
DE (1) DE69413901T2 (ja)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6169536B1 (en) * 1996-06-04 2001-01-02 Lg Electronics Inc. Color picture quality compensation circuit and related control method thereof
US20060227242A1 (en) * 2005-04-12 2006-10-12 Po-Wei Chao Method and apparatus of deinterlacing
US20060228022A1 (en) * 2005-04-12 2006-10-12 Po-Wei Chao Method and apparatus of false color suppression
US20070097392A1 (en) * 2005-10-27 2007-05-03 Princeton Technology Corporation Image compensation device and method
US20120162285A1 (en) * 2010-12-28 2012-06-28 Sony Corporation Signal processing device, signal processing method, display device, and electronic apparatus

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6396599B1 (en) * 1998-12-21 2002-05-28 Eastman Kodak Company Method and apparatus for modifying a portion of an image in accordance with colorimetric parameters
KR100662341B1 (ko) * 2004-07-09 2007-01-02 엘지전자 주식회사 디스플레이 장치 및 그의 색 재현 방법
CN101754031B (zh) * 2008-12-08 2012-09-05 康佳集团股份有限公司 一种电视机场幅温度补偿电路
CN101853644B (zh) * 2010-06-13 2012-04-11 友达光电股份有限公司 显示器及显示器的颜色调整方法

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3760099A (en) * 1971-11-01 1973-09-18 Tektronix Inc Video amplifier for a color television apparatus
US4369466A (en) * 1979-11-26 1983-01-18 Sony Corporation Video signal processing circuit
JPH02107092A (ja) * 1988-10-17 1990-04-19 Sanyo Electric Co Ltd カラーテレビジョン受像機
JPH02192286A (ja) * 1989-01-19 1990-07-30 Matsushita Electric Ind Co Ltd カラーテレビジョン受像機
WO1991006180A2 (en) * 1989-10-16 1991-05-02 Eastman Kodak Company Method and apparatus for signal companding
JPH03135290A (ja) * 1989-10-20 1991-06-10 Victor Co Of Japan Ltd カラーディスプレイ装置
EP0460595A2 (en) * 1990-06-05 1991-12-11 Matsushita Electric Industrial Co., Ltd. Apparatus for correcting a black level of a video signal
JPH0477179A (ja) * 1990-07-17 1992-03-11 Matsushita Electric Ind Co Ltd 映像信号の階調補正装置
JPH04150171A (ja) * 1990-10-09 1992-05-22 Matsushita Electric Ind Co Ltd 階調補正方法および階調補正装置
JPH04229788A (ja) * 1990-08-06 1992-08-19 Sanyo Electric Co Ltd 映像信号処理回路
US5351141A (en) * 1992-01-09 1994-09-27 Matsushita Electric Industrial Co., Ltd. Video signal correction system

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5852391B2 (ja) * 1978-01-20 1983-11-22 松下電器産業株式会社 カラ−テレビジョン受像機の色信号処理装置
JPH02298194A (ja) * 1988-10-03 1990-12-10 Hitachi Ltd カラービデオプリンタ装置

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3760099A (en) * 1971-11-01 1973-09-18 Tektronix Inc Video amplifier for a color television apparatus
US4369466A (en) * 1979-11-26 1983-01-18 Sony Corporation Video signal processing circuit
JPH02107092A (ja) * 1988-10-17 1990-04-19 Sanyo Electric Co Ltd カラーテレビジョン受像機
JPH02192286A (ja) * 1989-01-19 1990-07-30 Matsushita Electric Ind Co Ltd カラーテレビジョン受像機
WO1991006180A2 (en) * 1989-10-16 1991-05-02 Eastman Kodak Company Method and apparatus for signal companding
JPH03135290A (ja) * 1989-10-20 1991-06-10 Victor Co Of Japan Ltd カラーディスプレイ装置
EP0460595A2 (en) * 1990-06-05 1991-12-11 Matsushita Electric Industrial Co., Ltd. Apparatus for correcting a black level of a video signal
JPH0477179A (ja) * 1990-07-17 1992-03-11 Matsushita Electric Ind Co Ltd 映像信号の階調補正装置
JPH04229788A (ja) * 1990-08-06 1992-08-19 Sanyo Electric Co Ltd 映像信号処理回路
JPH04150171A (ja) * 1990-10-09 1992-05-22 Matsushita Electric Ind Co Ltd 階調補正方法および階調補正装置
US5351141A (en) * 1992-01-09 1994-09-27 Matsushita Electric Industrial Co., Ltd. Video signal correction system

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6169536B1 (en) * 1996-06-04 2001-01-02 Lg Electronics Inc. Color picture quality compensation circuit and related control method thereof
US20060227242A1 (en) * 2005-04-12 2006-10-12 Po-Wei Chao Method and apparatus of deinterlacing
US20060228022A1 (en) * 2005-04-12 2006-10-12 Po-Wei Chao Method and apparatus of false color suppression
US7634132B2 (en) 2005-04-12 2009-12-15 Realtek Semiconductor Corp. Method and apparatus of false color suppression
US20100074522A1 (en) * 2005-04-12 2010-03-25 Po-Wei Chao Method and Apparatus of False Color Suppression
US7822271B2 (en) 2005-04-12 2010-10-26 Realtek Semiconductor Corp Method and apparatus of false color suppression
US7978265B2 (en) 2005-04-12 2011-07-12 Realtek Semiconductor Corp. Method and apparatus of deinterlacing
US20070097392A1 (en) * 2005-10-27 2007-05-03 Princeton Technology Corporation Image compensation device and method
US7577293B2 (en) * 2005-10-27 2009-08-18 Princeton Technology Corporation Image compensation device and method
US20120162285A1 (en) * 2010-12-28 2012-06-28 Sony Corporation Signal processing device, signal processing method, display device, and electronic apparatus
US8872867B2 (en) * 2010-12-28 2014-10-28 Sony Corporation Signal processing device, signal processing method, display device, and electronic apparatus

Also Published As

Publication number Publication date
KR950004980A (ko) 1995-02-18
KR970006659B1 (ko) 1997-04-29
JPH0746621A (ja) 1995-02-14
CN1085926C (zh) 2002-05-29
CA2128758A1 (en) 1995-01-29
EP0637166B1 (en) 1998-10-14
DE69413901T2 (de) 1999-03-04
EP0637166A1 (en) 1995-02-01
CN1107633A (zh) 1995-08-30
JP3136850B2 (ja) 2001-02-19
DE69413901D1 (de) 1998-11-19
AU674235B2 (en) 1996-12-12
CA2128758C (en) 1999-11-23
AU6742394A (en) 1995-02-09

Similar Documents

Publication Publication Date Title
KR930000462B1 (ko) 컬러텔레비젼 수상기
US5585860A (en) Reproduction circuit for skin color in video signals
RU2100911C1 (ru) Устройство для автоматической регулировки амплитуды видеосигнала
CA1154152A (en) Video signal processing circuit
US5191420A (en) Video system with feedback controlled "white stretch" processing and brightness compensation
US5841486A (en) Compensation voltage generating apparatus for multipicture display and video display including the same
KR930011182B1 (ko) 영상신호의 계조 보정장치
US5502508A (en) Gradation compensating apparatus for a video signal
EP0700208B1 (en) Automatic brightness contrast lighting circuits and luminance/color difference signal processor and video display apparatus comprising the same
US5432566A (en) Video circuit controlling brightness and/or saturation
US4354202A (en) Television receiver on-screen alphanumeric display
US4030125A (en) Automatic video processing for high-performance CRT displays
US5621479A (en) Method of driving a liquid crystal display device
US6580464B1 (en) Color difference signal correction apparatus
JPH05224641A (ja) 映像表示装置
JP3158768B2 (ja) 映像信号の色信号振幅制限装置
JP2938264B2 (ja) 液晶映像表示装置
JP3439452B2 (ja) 色差信号補正装置
JPS62269494A (ja) デイスプレイ機器のカラ−映像信号処理回路
JPH0573318B2 (ja)
JPH0638074A (ja) 画質調整回路
JP2003319413A (ja) 色差信号補正装置
JPH06350946A (ja) 投写形ディスプレイ装置
JPH0514840A (ja) 映像信号処理回路
JPH06178309A (ja) Ｒｇｂ映像信号処理回路

Legal Events

Date Code Title Description
AS Assignment

Owner name: MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD., JAPAN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:KAWABATA, MINORU;KAGEYAMA, ATSUHISA;REEL/FRAME:007117/0282

Effective date: 19940808

FEPP Fee payment procedure

Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

STCF Information on status: patent grant

Free format text: PATENTED CASE

FPAY Fee payment

Year of fee payment: 4

FPAY Fee payment

Year of fee payment: 8

FPAY Fee payment

Year of fee payment: 12